Which of these numbers is composite? ${37,\ 61,\ 67,\ 75,\ 89}$
Explanation: A composite number is a number that has more than two factors (including 1 and itself). 37, 61, 67, and 89 each have only two factors. The factors of 75 are 1, 3, 5, 15, 25, and 75. Thus, 75 is the composite number.